Catechism of the Catholic Church

Song and music fulfill their function as signs in a manner all the more significant when they are "more closely connected... with the liturgical action," according to three principal criteria: beauty expressive of prayer, the unanimous participation of the assembly at the designated moments, and the solemn character of the celebration. In this way they participate in the purpose of the liturgical words and actions: the glory of God and the sanctification of the faithful: (2502) > How I wept, deeply moved by your hymns, songs, and the voices that echoed through your Church! What emotion I experienced in them! Those sounds flowed into my ears, distilling the truth in my heart. A feeling of devotion surged within me, and tears streamed down my face-tears that did me good.